a) Field of the Invention
This invention relates generally to the field of concrete form construction, and more particularly to the tie-rod assemblies which position the two form wall sections at the proper spacing distance from on another.
b) Background Art
A common method of constructing concrete walls is to form two wall form sections which have inner forming surfaces facing each other and spaced from each other by a distance equal to the thickness of the wall to be formed. Commonly, each of these walls is made of panels (e.g. 4′×8′ plywood panels), with each set of panels being placed in a common plane. To maintain the panels properly spaced with respect to one another, there is commonly provided a bracing/positioning structure in the form of sets of horizontally extending walers and vertically aligned strongbacks which bear against the outside surface of the panels. Through openings are drilled through the walers and through the panels, and tie-rods extend through matching pairs of aligned openings formed in the two wall form sections. Then retaining members are connected to each outer end of the tie-rod, such as a wing nut or other nut which is threaded onto the end of the tie-rod to press against a metal bearing plate that in turn bears against the outside surface of one of the walers.
With the two wall form sections being properly positioned and spaced from one another, and with the tie assemblies (i.e. the tie-rods and the retaining devices) properly in place, then the pour of the concrete can proceed. Quite commonly, there are metal reinforcing rods and/or other reinforcing members positioned in the receiving area of the concrete to form the concrete wall or other concrete structure in the form of reinforced concrete. After the concrete has cured sufficiently, either or both of the retaining members are removed from each tie-rod, the tie-rods removed, and the two wall form sections are taken down and are generally at least partially disassembled in some manner.
Obviously, if the tie-rod is to be removed from the hardened concrete, provisions must be made to avoid the central portion of the tie-rod that is in the region of the concrete pour from becoming embedded in the concrete. Accordingly, there have been various attempts in the prior art to address this problem.
Further, in addition to the problem of removing the tie-rods, there have also been various arrangements to properly space the surfaces of the two form wall sections from one another. In other instances, such spacing devices are not used, and the force of the concrete in the receiving area bearing against the inside forming surfaces of the form wall sections (being held in place by the tie-rods) is depended upon to ensure the uniform thickness of the wall.
Two of the patents which are of interest are U.S. Pat. No. 4,044,986 (Strickland et al.) and U.S. Pat. No. 4,159,097 (Strickland). Both of these patents will be discussed later in this text after the brief description of the drawings, and in this section on background art, they will be discussed only briefly.
The earlier of these two patents (i.e. U.S. Pat. No. 4,044,986) relates primarily to various devices to anchor the tie-rods (in U.S. Pat. No. 4,044,986 called the “tie”). In FIGS. 20, 21, and 22, there are shown three tie-rod configurations of interest. These are discussed in the text of the patent beginning in column 9, line 42, and continuing on through most of column 10. It is stated that “. . . other forms of tie are equally suitable to practicing this invention. More particularly, solid ties preferably having a continuous taper, such as those illustrated in FIGS. 20, 21, and 22, may also be used to practice this invention. After the concrete structure has set, the continuous taper of these ties permits them to be driven out of engagement with the structure.”
Each of the tie-rods shown in these three figures (FIGS. 20, 21, and 22) appear to be made from a single piece of metal (or at least made as on integral metal piece), and they differ mainly in the configuration of the end retaining sections that connect to a retainer so that the tension can be applied to the tie-rod.
The second patent of interest (U.S. Pat. No. 4,159,097) names Strickland (the first-named co-inventor of the early above-noted patent U.S. Pat. No. 4,044,986) as the sole inventor. In the introductory text of that patent (column 1, beginning on line 13), reference is made to U.S. Pat. No. 4,044,986, and it is stated that one of the features in the apparatus is the use of a tapered tie-rod. It is further stated that such tie-rods are conventionally made from a plurality of steel rods threaded together or cast into a one-piece steel tie that has sufficient strength to hold the form panels together and withstand the stresses imposed upon the ties. The patent goes on to recite the certain deficiencies in that design, and these will be discussed later in the text of this application.
The tie-rod in U.S. Pat. No. 4,159,097 differs from that of the earlier patent (U.S. Pat. No. 4,044,986) in that the tapered portion of the tie-rod is not made of steel and formed as part of the metal piece, but rather is made from a plastic sleeve that is firmly attached to the steel tie-rod. The reasons for this will be discussed later in this text.
A search of the U.S. patent literature has disclosed a number of other patents generally relevant to this technology of providing concrete forms, and each of these are discussed briefly below.
U.S. Pat. No. 5,282,603 (Taraldsson) relates to a clamping device to be used in concrete forms. In FIG. 1, there is shown a sealing element 7 which comprises two compressible end seals 27 & 28, and a frusto-conical center member 29 having a moderate taper and which is made of a relatively non-compressible material. When the tie-rod is tensioned, the sealing elements 27 & 28 close the two openings 8 & 9 in the forming boards 2.
U.S. Pat. No. 4,726,560 (Dotson) shows a concrete form tie assembly where there is a flexible plastic sleeve 20 which is placed over the tie-rod. There is a cone-shaped member 54 to act as a means of fixedly locating one end of the assembly 10.
U.S. Pat. No. 4,109,893 (Laroche) shows a conical mold panel spacer.
U.S. Pat. No. 3,648,961 (Farrow) discloses a wall tie for concrete forms. There is a tie-rod which extends through a spacer or spreader 32 which has a frusto-conical shape with a moderate taper. The operating position is at a location between the two boards of the concrete forming assembly and keeps the two boards spaced at the proper distance from one another. At one end of the spacer 32, the tie-rod has a threaded end member 44 on which a nut is threaded, and there are two washers 46 & 48 positioned on opposite sides of this threaded member 44. In the assembled position, as we had seen in FIG. 3, this nut 50 with the two washers 46 & 48 properly locates the spacer 32.
U.S. Pat. No. 2,709,292 (Otti) relates primarily to a clamp for concrete forms. There is shown a frusto-conical spacing member 20 having a moderate slant with the larger end bearing against the board member 12 and the opposite end bearing against the other board.
U.S. Pat. No. 2,502,672 (Royther) discloses a tie-rod having a spreader or spacing member 6 which has threaded sockets on opposite sides. The tie-rod comprises two threaded members which are threaded into the end holes 8 & 9. The purpose of this is that when the concrete is being set, these function as a spacer. However, the spacers do not need to be removed until the concrete has hardened, this being due to the fact that the nuts can be unthreaded from the ends of the tie-rod while the spacer remains in place. After that, then the spacer can be removed.
U.S. Pat. No. 1,436,345 (Jackson) shows a tie-bar and a spacer. The spacer 13 is a frusto-conical member with a moderate taper and it is positioned between two opposing forming walls. In FIG. 10, the spacer is shown being used to form a double-wall container or other member.